The demand for liner-carried dry labels has existed for many years, and various attempts have been made to meet this demand. These attempts have had limited success because of quality and cost problems and lack of manufacturing versatility.
One prior approach was to extrude polyethylene on facestock for a label to make up a facestock construction in which the facestock proper and the extruded polyethylene layer were permanently combined. This facestock construction, consisting of the facestock proper with its extruded polyethylene layer, was then combined with a liner construction. The liner construction consisted of a film of copolymer permanently adhered to a liner proper such as a web of paper liner. The extruded polyethylene of the facestock construction and the copolymer film of the liner construction were in contact and were intended to releasably hold the combined construction together, the interface between them being intended as the release interface of the product. When individual labels were formed, the die-cutting would, of course, extend through the facestock construction, but not through the copolymer film of the liner construction. When the individual labels or tags formed from the facestock construction were finally removed from the liner construction, they would be non-tacky or dry on both sides. This product was not reliable because the copolymer release from the polyethylene coated facestock was difficult to control. Also, manufacturing dry labels using a variety of facestocks required that each facestock be separately extrusion-coated with polyethylene. This was a costly requirement and greatly limited the variety and availability of facestocks.
Another prior art approach also formed the liner construction as a copolymer layer permanently adhered to a liner web proper. A film layer was applied over the copolymer layer in the same coating line pass in which the liner construction was formed. In a second pass, facestock was permanently adhered to the film layer to complete the facestock constructions, such facestock construction consisting of the film layer and the facestock proper adhered thereto. The interface between the film layer and the copolymer layer was intended as the release interface of the product at which the combined constructions were to be releasably held together. This product was also not reliable because the copolymer did not always provide a continuous film to completely cover the adhesive used to permanently adhere the copolymer to the liner proper. Also the product was costly because its manufacture required two passes on the coating line.
An early prior disclosure is that of Komendat and Reed U.S. Patent 3,769,147 to an assignee that is predecessor to present assignee. In this patent preformed heat softening film material 11 such as polyethylene film is laminated between a "mutable web" 10 and a base or backing 12 (FIGS. 1 and 3). The disclosure also mentions (at col. 5, line 55) coating a layer of polyethylene 26 on the backing 27 (FIG. 4) prior to lamination to the "mutable web" 31. The intention is to permanently carry the polyethylene 26 on the backing 27. Later separation occurs at the interface between elements 26 and 31.
Besides dealing with the handling and processing of "mutable webs", the Komendat and Reed patent also deals specifically with dry tags and labels, but in that instance solution-coated copolymer of vinylidene chloride and vinyl chloride (SARAN) is mentioned rather than polyethylene. The construction is shown in FIG. 6 and includes the liner or backing 63, the coating 62 of copolymer solution-coated on the backing 63, and tag stock 61 laminated to the coating 62. The tag stock is formed into tags 66 and matrix portions 68. Separation is intended to occur at the interface between the tag stock 61 and the copolymer 62. This approach is not believed to have ever come into successful use.
A still earlier prior disclosure is that of Kennedy U.S. Patent 3,420,364 assigned to Dennison Manufacturing Company. This disclosure is difficult to follow because of appararent inconsistencies (e.g. a release layer 4 is disclosed as covering a lacquer coating 3 which in turn covers a layer 2 of pressure sensitive adhesive, yet the disclosure says that the release layer should adhere to the pressure sensitive adhesive more strongly than to the lacquer) but it does reflect a prior art effort to provide liner-carried dry tag.
All of the above manufactured or disclosed products had a carry-release component shared between the facestock construction and the liner construction and consisting of the layers forming the release interface. In the first case, the carry-release component consisted of the copolymer layer and the layer of extruded polyethylene which had been laminated to the copolymer layer. In the second case, the carry-release component consisted of the copolymer layer and the film layer which had been coated on the copolymer layer. In the FIG. 6 construction of Komendat and Reed, the carry-release component consisted of the tag stock 61 and the copolymer 62 which had been coated thereon. In the Kennedy construction, the lacquer coating 3 and release material 4 seen in FIG. 2 appear to be intended to comprise a carry-release component.